US4645895A
Expired / Lapsed
US
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Method and apparatus for surface-treating workpieces
Assignee: Ramot at Tel Aviv University Ltd
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Filing: 1985-04-03
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Granted: 1987-02-24
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Expires: 2005-04-03
Abstract
Abstract A method of surface-treating a workpiece is described characterized in applying one or more short-duration electrical pulses to produce, for each pulse, a high amplitude short-duration electrical discharge between the workpiece, serving as an anode, and another material serving as a cathode, while the workpiece and cathode are in a vacuum ambient. The workpiece and cathode are spaced from each other by a gap which is less than the smallest dimension of the cathode in the plane therethrough parallel to the workpiece.
Inventors
- 👤 Raymond L. Boxman
- 👤 Shmuel Goldsmith
- 👤 Nissan Brosh
- 👤 Shaul Shalev
- 👤 Hanan Yaloz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 22:48
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/32; H01J37/32009; H01J37/32055; B; B23; B23K; B23K28/00; B23K28/003; B23K35/00; B23K35/22; B23K35/24; C; C23; C23C; C23C14/00; C23C14/22; C23C14/24; C23C14/32; C23C26/00; C23C26/02
Claims Analysis
Total Claims: 43
Claim 1
Independent Claim
50 words
The method of surface treating a workpiece, characterized in applying one or more short-duration electrical pulses to produce, for each pulse, a high-amplitude short-duration electrical discharge between said workpiece, serving as an anode, and another material serving as a cathode, while said workpiece and cathode are in a vacuum ambient.
Claim 2
Independent Claim
50 words
The method of surface treating a workpiece, characterized in applying one or more short-duration electrical pulses to produce, for each pulse, a high-amplitude short-duration electrical discharge between said workpiece, serving as an anode, and another material serving as a cathode, while said workpiece and cathode are in a vacuum ambient.
Claim 3
Dependent Claim
37 words
The method according to claim 1, wherein said workpiece and cathode are spaced from each other by a gap which is less than the smallest dimension of said cathode in the plane therethrough parallel to said workpiece.
Claim 4
Dependent Claim
22 words
The method according to claim 1, wherein each of said pulses is applied for a duration (HAFW) of 0.5 to 100 ms.
Claim 5
Dependent Claim
24 words
The method according to claim 1, wherein each of said electrical discharges has a current density of at least 3·10 6 amps/m 2 .
Claim 6
Dependent Claim
20 words
The method according to claim 1, wherein each of said electrical discharges has a current of at least 500 amps.
Claim 7
Dependent Claim
19 words
The method according to claim 5, wherein each of said electrical discharges has a current of from 500-2000 amps.
Claim 8
Dependent Claim
23 words
The method according to claim 1, wherein said cathode diameter is at least 10 mm., and said workpiece is spaced therefrom 1-8 mm.
Claim 9
Dependent Claim
49 words
The method according to claim 1, wherein the material of said cathode is applied as a surface coating to said workpiece, the surface of the workpiece being heated by said electrical discharge above the melting point of the cathode material, but below the melting point of the workpiece material.
Claim 10
Dependent Claim
47 words
The method according to claim 1, wherein the material of said cathode is applied as a surface coating to said workpiece, the surface of the workpiece being heated by said electrical discharge sufficiently to promote interdiffusion of, and thereby adhesion between, said workpiece and said cathode coating.
Claim 11
Dependent Claim
59 words
The method according to claim 1, wherein the material of said cathode is applied as a surface coating to said workpiece, the surface of said workpiece being heated by said electrical discharge above the melting point of the cathode material and of the workpiece material, thereby producing an alloy of the two materials on the surface of the workpiece.
Claim 12
Dependent Claim
57 words
The method according to claim 1, wherein the surface of said workpiece is heated by said electrical discharge beyond its solid phase transformation temperature and then is allowed to rapidly cool through natural solid conduction into the bulk of the workpiece material, thereby quenching the regions near the surface of the workpiece to induce metastable crystalline structure.
Claim 13
Dependent Claim
22 words
The method according to claim 1, wherein each of said electrical discharges is produced only at selected areas of the workpiece surface.
Claim 14
Dependent Claim
18 words
The method according to claim 1, wherein each of said electrical discharges is initiated by a triggering device.
Claim 15
Dependent Claim
25 words
The method according to claim 1, wherein an alloying gas is present in said vacuum ambient at the time of each of said electrical discharges.
Claim 16
Dependent Claim
38 words
The method according to claim 1, wherein each of said electrical discharges is produced between said workpiece and a plurality of cathodes, the latter producing a plurality of plasma beams which merge at the surface of said workpiece.
Claim 17
Dependent Claim
40 words
The method according to claim 1, wherein a magnetic field is produced axially of the gap between said workpiece and cathode at the time of each of said electrical discharges to collimate the plasma flow between the workpiece and cathode.
Claim 18
Dependent Claim
28 words
The method according to claim 1, wherein the workpiece is of a long cylindrical configuration, and there are a plurality of said cathodes disposed around said cylindrical workpiece.
Claim 19
Dependent Claim
50 words
The method according to claim 1, wherein there are a plurality of cathodes of different materials closely spaced to said workpiece, there being at least one short-duration, high-amplitude electrical pulse sequentially applied between each cathode and the workpiece to produce on the workpiece successive coatings of the different cathode materials.
Claim 20
Dependent Claim
28 words
The method according to claim 1, wherein said workpiece is of long, hollow configuration, and said cathode is disposed within said workpiece to treat the inner surface thereof.
Claim 21
Dependent Claim
28 words
The method according to claim 19, wherein the cathode is moved along the length of the long, hollow workpiece to treat different portions of the inner surface thereof.
Claim 22
Dependent Claim
23 words
The method according to claim 19, including the further step of introducing an alloying gas into said chamber between the cathode and workpiece.
Claim 23
Independent Claim
44 words
The method of surface treating a long, hollow workpiece comprising: disposing said workpiece in a vacuum chamber; disposing a cathode within said workpiece; and applying electrical pulses between said cathode and said workpiece to produce electrical discharges therebetween, the workpiece serving as an anode.
Claim 24
Independent Claim
44 words
The method of surface treating a long, hollow workpiece comprising: disposing said workpiece in a vacuum chamber; disposing a cathode within said workpiece; and applying electrical pulses between said cathode and said workpiece to produce electrical discharges therebetween, the workpiece serving as an anode.
Claim 25
Dependent Claim
65 words
Apparatus for surface-treating a workpiece, comprising: a vacuum chamber; first support means for supporting the workpiece in said vacuum chamber to serve as an anode; second support means for supporting another material in said vacuum chamber to serve as a cathode; and means for applying short-duration electrical pulses between said workpiece and said cathode to produce, for each pulse, a high-amplitude, short-duration electrical discharge therebetween.
Claim 26
Dependent Claim
65 words
Apparatus for surface-treating a workpiece, comprising: a vacuum chamber; first support means for supporting the workpiece in said vacuum chamber to serve as an anode; second support means for supporting another material in said vacuum chamber to serve as a cathode; and means for applying short-duration electrical pulses between said workpiece and said cathode to produce, for each pulse, a high-amplitude, short-duration electrical discharge therebetween.
Claim 27
Dependent Claim
48 words
Apparatus according to claim 23, wherein said first and second support means are spaced from each other to support said workpiece and cathode spaced from each other by a gap which is less than the smallest dimension of the cathode in the plane therethrough parallel to the workpiece.
Claim 28
Dependent Claim
37 words
Apparatus according to claim 24, wherein said first and second support means are spaced from each other to support said workpiece and cathode spaced from each other by a gap which is no more than 8 mm.
Claim 29
Dependent Claim
15 words
Apparatus according to claim 23, further including a triggering device for initiating the electrical discharges.
Claim 30
Dependent Claim
24 words
Apparatus according to claim 23, further including means for introducing an alloying gas into said vacuum chamber at the time of each electrical discharge.
Claim 31
Dependent Claim
91 words
Apparatus according to claim 27, wherein said cathode is formed with a hol1ow cavity in its interior, and with a plurality of holes connecting said cavity with the cathode surface normally facing the workpiece, said apparatus further including means providing a regulated gas flow to said cavity and to said holes of the cathode such that the gas may be injected in close proximity to cathode spots formed of the surface of the cathode and thus produce a combined plasma flow of the gas mixed with the material from the cathode.
Claim 32
Dependent Claim
105 words
Apparatus for surface-treating a workpiece, comprising: a vacuum chamber; first support means for supporting the workpiece in said vacuum chamber to serve as an anode; a cathode having a hollow cavity in its interior, and a plurality of holes connecting said cavity with the cathode surface normally facing the workpiece; and means providing a regulated gas flow to said cavity and said plurality of holes of the cathode such that the gas may be injected in close proximity to cathode spots formed on the surface of the cathode and thus produce a combined plasma flow of the gas mixed with the material from the cathode.
Claim 33
Dependent Claim
105 words
Apparatus for surface-treating a workpiece, comprising: a vacuum chamber; first support means for supporting the workpiece in said vacuum chamber to serve as an anode; a cathode having a hollow cavity in its interior, and a plurality of holes connecting said cavity with the cathode surface normally facing the workpiece; and means providing a regulated gas flow to said cavity and said plurality of holes of the cathode such that the gas may be injected in close proximity to cathode spots formed on the surface of the cathode and thus produce a combined plasma flow of the gas mixed with the material from the cathode.
Claim 34
Dependent Claim
30 words
Apparatus according to claim 29, wherein said second support means supports a plurality of cathodes to produce a plurality of plasma beams which merge at the surface of the workpiece.
Claim 35
Dependent Claim
41 words
Apparatus according to claim 29, further including means for producing a magnetic field axially of the gap between said workpiece and cathode at the time of each of said electrical discharges to collimate the plasma flow between the workpiece and cathode.
Claim 36
Dependent Claim
36 words
Apparatus according to claim 29, wherein said first support means is adapted to support a workpiece of long, hollow configuration, and said second support means is adapted to support a cathode within such long, hollow workpiece.
Claim 37
Dependent Claim
65 words
Apparatus for treating the inner surface of a workpiece of long, hollow configuration comprising: a vacuum chamber; first support means for supporting the workpiece in said vacuum chamber to serve as an anode; second support means for supporting a cathode at selected locations within said long, hollow workpiece; and means for applying electrical pulses between said workpiece and said cathode to produce electrical discharges therebetween.
Claim 38
Dependent Claim
65 words
Apparatus for treating the inner surface of a workpiece of long, hollow configuration comprising: a vacuum chamber; first support means for supporting the workpiece in said vacuum chamber to serve as an anode; second support means for supporting a cathode at selected locations within said long, hollow workpiece; and means for applying electrical pulses between said workpiece and said cathode to produce electrical discharges therebetween.
Claim 39
Dependent Claim
32 words
Apparatus according to claim 33, wherein said second support means includes means for moving the cathode along the length of the long, hollow workpiece to treat different portions of its inner surface.
Claim 40
Dependent Claim
64 words
Apparatus according to claim 33, wherein said first support means supports the long cylindrical workpiece such that it can protrude from the ends of the vacuum chamber via vacuum seals; said apparatus including an array of cathodes disposed around the circumference of the workpiece at a selected longitudinal location thereon; and current supply means for equally distributing the current among said plurality of cathodes.
Claim 41
Dependent Claim
96 words
Apparatus for treating the inner surface of selected longitudinal regions of a long cylindrical workpiece, comprising: a vacuum chamber; means for supporting said long cylindrical workpiece in said vacuum chamber with its ends protruding therefrom via vacuum seals; an array of cathode assemblies disposed around the circumference of the workpiece at a selected longitudinal location thereon; and a current supply providing current to said plurality of cathodes so as to produce electrical discharges between said plurality of cathodes so as to produce electrical discharges between said plurality of cathodes and said workpiece serving as an anode.
Claim 42
Dependent Claim
96 words
Apparatus for treating the inner surface of selected longitudinal regions of a long cylindrical workpiece, comprising: a vacuum chamber; means for supporting said long cylindrical workpiece in said vacuum chamber with its ends protruding therefrom via vacuum seals; an array of cathode assemblies disposed around the circumference of the workpiece at a selected longitudinal location thereon; and a current supply providing current to said plurality of cathodes so as to produce electrical discharges between said plurality of cathodes so as to produce electrical discharges between said plurality of cathodes and said workpiece serving as an anode.
Claim 43
Dependent Claim
24 words
Apparatus according to claim 36 further including means for introducing an alloying gas into said chamber between the cathode and the long, cylindrical workpiece.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-02-23 | 1990-08-25 | 1991-02-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-02-23 | 1994-08-25 | 1995-02-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-02-23 | 1998-08-25 | 1999-02-24 | $7700.00 | Window Closed / Lapsed |